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Memory of Chirality in Flow Electrochemistry: Fast Optimisation with DoE and Online 2D-HPLC

Articles from Wiley - 21 November, 2019 - 00:00

Asymmetric transformations are quickly optimised using a DoE-approach with an electrochemical flow reactor attached to a 2D-HPLC. Cyclic and acyclic N,O-acetals were obtained in moderate to good yields and enantioselectivities. The highly reactive acyliminium ion serves as a chiral intermediate leading to the desired product with ‘memorised“ chirality (up to 70 % ee, see scheme) in a short reaction time.

[Communications]
Micol Santi, Jakob Seitz, Rossana Cicala, Tomas Hardwick, Dr. Nisar Ahmed, Prof. Dr. Thomas Wirth
doi.org/10.1002/chem.201904711

Lead(II) Siloxides

Articles from Wiley - 21 November, 2019 - 00:00

Stable lead(II) siloxides that do not decompose to oxoclusters have been prepared. These include the first homoleptic PbII-siloxide, which also exhibits unique structural features.

[Communications]
Adrian-Alexandru Someşan, Erwann Le Coz, Dr. Ciprian Ionuţ Raţ, Dr. Vincent Dorcet, Dr. Thierry Roisnel, Prof. Dr. Cristian Silvestru, Dr. Yann Sarazin
doi.org/10.1002/chem.201904713

Star-Shaped Ruthenium Complexes as Prototypes of Molecular Gears

Articles from Wiley - 21 November, 2019 - 00:00

Geared up: Two families of molecular-gear prototypes were designed and synthesized by a divergent approach, with the aim of achieving controlled intermolecular gearing on a surface. The seven star-shaped ruthenium complexes incorporate a pentaarylcyclopentadienyl ligand as cogwheel, equipped with teeth ranging from pseudo-1D biphenyl groups to planar carbazole-, BODIPY-, and porphyrin-derived 2D paddles (see figure).

[Full Papers]
Guillaume Erbland, Dr. Seifallah Abid, Yohan Gisbert, Nathalie Saffon-Merceron, Yuichiro Hashimoto, Leonardo Andreoni, Théo Guérin, Dr. Claire Kammerer, Prof. Dr. Gwénaël Rapenne
doi.org/10.1002/chem.201903615

A General Strategy for Through-Bond Energy Transfer Fluorescence Probes Combining Intramolecular Charge Transfer: A Silyl Ether System for Endogenous Peroxynitrite Sensing

Articles from Wiley - 21 November, 2019 - 00:00

Sensing change: A probe has been developed that provides: 1) a general design strategy for TBET probes; 2) a mechanism of silyl ether cleavage by ONOOH; and 3) a TBET fluorescence probe design based on only one fluorophore for endogenous ONOO−. The probe shows high selectivity, large pseudo-Stokes shift (213 nm) and large emission shift (179 nm shift; see scheme).

[Full Papers]
Dr. Gonghao Lu, Yuxin Guo, Jiezhen Zhuo, Dr. Xue Li, Haijun Chi, Prof. Dr. Zhiqiang Zhang
doi.org/10.1002/chem.201903880

Hexabenzocoronene Graphitic Nanocoils Appended with Crown Ethers: Supramolecular Chirality Induced by Host-Guest Interaction

Articles from Wiley - 21 November, 2019 - 00:00

Spiral tap: In this work, a simple and commercially available amino acid was used as chiral source for the noncovalent assembly of a hexabenzocoronene derivative, HBCCE, to produce a helix sense-selective and helical memory nanocoiled architecture (see graphic).

[Full Papers]
Wang Zeng, Wei Zhang, Xianying Li, Wusong Jin, Dengqing Zhang
doi.org/10.1002/chem.201904291

Metal-Free Aryl Cross-Coupling Directed by Traceless Linkers

Articles from Wiley - 21 November, 2019 - 00:00

Without a trace: The scope and mechanism of (hetero)biaryl synthesis by photochemical fusion of aryl substituents tethered to a traceless sulfonamide linker (photosplicing) are reported. The reaction has a broad scope and involves neither metals nor radicals. Theoretical calculations revealed that the C−C bond is formed by an intramolecular photochemical process that is initiated by formation of a U-shaped conformation, involves an excited singlet state and traversal of a five-membered transition state, and thus consistently results in ipso-ipso coupling.

[Full Papers]
Veit G. Haensch, Toni Neuwirth, Johannes Steinmetzer, Dr. Florian Kloss, Prof. Dr. Rainer Beckert, Prof. Dr. Stefanie Gräfe, Dr. Stephan Kupfer, Prof. Dr. Christian Hertweck
doi.org/10.1002/chem.201903582

A Quantitative Analysis of the Reduction Kinetics Involved in the Synthesis of Au@Pd Concave Nanocubes

Articles from Wiley - 21 November, 2019 - 00:00

Not just a cap! The role played by the capping agent in controlling the reduction kinetics of a PdII precursor for the formation of Au@Pd concave nanocubes with distinctive shapes or morphologies was systematically studied. It is shown that the capping agent can impact the reduction kinetics of a precursor, and thereby its reduction pathway, for the formation of metal nanocrystals with distinct morphologies (see figure).

[Full Papers]
Minghao Xie, Dr. Shan Zhou, Jiawei Zhu, Zhiheng Lyu, Ruhui Chen, Prof. Dr. Younan Xia
doi.org/10.1002/chem.201904074

Electrochemical Approach for the Production of Layered Double Hydroxides with a Well-Defined Co/Me<sup>III</sup> Ratio

Articles from Wiley - 21 November, 2019 - 00:00

Make a deposit: Layered double hydroxides (LDHs) are prepared using different ratios of the trivalent (Fe or Al) to bivalent (Co) cations by an efficient electrochemical route and are reported as highly active OER catalysts.

[Full Papers]
Elisa Musella, Dr. Isacco Gualandi, Dr. Erika Scavetta, Dr. Massimo Gazzano, Arianna Rivalta, Dr. Elisabetta Venuti, Dr. Meganne Christian, Dr. Vittorio Morandi, Prof. Dr. Domenica Tonelli
doi.org/10.1002/chem.201903288

Central-to-Axial Chirality Conversion Approach Designed on Organocatalytic Enantioselective Povarov Cycloadditions: First Access to Configurationally Stable Indole-Quinoline Atropisomers

Articles from Wiley - 21 November, 2019 - 00:00

The Atropovarov reaction: The first stereoselective synthesis of enantioenriched axially chiral indole-quinoline systems is presented. The strategy takes advantage of an organocatalytic enantioselective Povarov cycloaddition of 3-alkenylindoles and N-arylimines, followed by an oxidative central-to-axial chirality conversion process.

[Full Papers]
Giorgiana Denisa Bisag, Daniel Pecorari, Prof. Dr. Andrea Mazzanti, Prof. Dr. Luca Bernardi, Prof. Dr. Mariafrancesca Fochi, Prof. Dr. Giorgio Bencivenni, Dr. Giulio Bertuzzi, Dr. Vasco Corti
doi.org/10.1002/chem.201904213

Impact of A-D-A-Structured Dithienosilole- and Phenoxazine-Based Small Molecular Material for Bulk Heterojunction and Dopant-Free Perovskite Solar Cells

Articles from Wiley - 21 November, 2019 - 00:00

One for all: A small molecule based on an acceptor-donor-acceptor array was synthesized and its dual function as part of either bulk heterojunction organic solar cells (BHJ OSCs) or perovskite solar cells (PSCs) was investigated.

[Full Papers]
Dr. Kamatham Narayanaswamy, Bommaramoni Yadagiri, Towhid Hossain Chowdhury, Thokala Swetha, Ashraful Islam, Dr. Vinay Gupta, Dr. Surya Prakash Singh
doi.org/10.1002/chem.201903599

Spontaneous Growth of 3D Silver Mesoflowers on Poly(4-vinylpyridine) Brushes-Grafted-Graphene Oxide Films and Facile Creation of Nanoporosities over their Surface

Articles from Wiley - 21 November, 2019 - 00:00

Sensing with flowers: 3D Ag mesoflowers (Ag MFs) with tunable size and shapes are spontaneously grown on poly(4-vinylpyridine) brushes-grafted-graphene oxide (P4VP-g-GO) films in Ag(NH3)2OH solution without the use of any additional reducing agent (see scheme). The obtained Ag MFs could be facilely converted into Ag nanoporous MFs (Ag NMFs) with ultrasensitivity in surface-enhanced Raman spectroscopy (SERS) detection.

[Full Papers]
Lihua Feng, Prof. Wenqin Wang, Xiyong Li, Prof. Tao Chen
doi.org/10.1002/chem.201903959

Preparation of an Anti-Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity

Articles from Wiley - 21 November, 2019 - 00:00

Nanocomposite adsorbents: A nano-silica/zinc/graphene oxide composite (GO-NMSZ) with good adsorption capacity and filtration efficiency has been prepared. The large number of active metal sites and high degree of oxidation of the GO sheets result in a multi-effect mechanism involving nonselective chemical and physical adsorption. These characteristics make GO-NMSZ applicable in the purification of dye-containing wastewater.

[Full Papers]
Yajun Yue, Dr. Zhanfang Cao, Fan Yang, Jing Wang, Dr. Isaac Abrahams
doi.org/10.1002/chem.201903875

Solvent-Free Synthesis of Zeolitic Imidazolate Frameworks and the Catalytic Properties of Their Carbon Materials

Articles from Wiley - 21 November, 2019 - 00:00

Shake and bake to ZIF: Metal oxides and 2-methylimidazole combine into zeolitic imidazolate frameworks in the absence of solvent and the ZIF-derived porous carbons synthesized by templating with eutectic salts show impressive electrocatalytic properties for the oxygen reduction reaction.

[Full Papers]
Yuchen Xiao, Anh N. Hong, Dandan Hu, Yanxiang Wang, Prof. Xianhui Bu, Prof. Pingyun Feng
doi.org/10.1002/chem.201903888

Solid-State <sup>13</sup>C NMR Evidence for Long Multicenter Intradimer Bonding in Zwitterion-like Structures

Articles from Wiley - 21 November, 2019 - 00:00

The principal values of the 13C chemical shift tensor for the β and δ polymorphs of π-[TTF⋅⋅⋅TCNE] (TTF=tetrathiafulvalene; TCNE=tetracyanoethylene) have been analyzed to understand the abnormally long intra-dimer bonding of singlet π-[TTFδ+⋅⋅⋅TCNEδ−]. This solid-state NMR study compares the [TTF⋅⋅⋅TCNE] 13C tensor data against previously reported π-[TTF]22+ and π-[TCNE]22− homo-dimers to determine how the tensor principal values change as a function of electronic structure for both TTF and TCNE moieties.

[Full Papers]
Alexander B. Elliott, Geraldine Versfeld, Merrill D. Halling, Prof. Joel S. Miller, Prof. James K. Harper
doi.org/10.1002/chem.201903099

Exploring Organic Metal Halides with Reversible Temperature-Responsive Dual-Emissive Photoluminescence

Articles from Wiley - 21 November, 2019 - 00:00

Emission accomplished: Sensitive and thermoresponsive dual emission is detected in pure single crystals of the organic metal halide (C4H9NH3)2MnI4. Temperature variation changes the relative intensity of the two emissions, leading to a clear transition of the emission color, which makes this new class of intrinsic dual-emitters attractive for optical thermometry applications.

[Communications]
Xiaomei Jiang, Prof. Dr. Shengqing Xia, Dr. Jian Zhang, Dr. Dianxing Ju, Prof. Dr. Yang Liu, Prof. Dr. Xiaobo Hu, Dr. Lei Wang, Prof. Dr. Zhaolai Chen, Prof. Dr. Xutang Tao
doi.org/10.1002/cssc.201902481

Iodine Promoted One-Pot Synthesis of 2-Aryl Benzoxazoles from Amidoximes via Oxidative Cyclization and Ring Contraction

Articles from Wiley - 21 November, 2019 - 00:00

An I2-promoted sequential oxidative cyclization and ring contraction reaction is developed for the synthesis of 2-aryl benzoxazoles by using amidoximes rather than the limited 2-aminophenols or 2-haloamides as substrates. This method provides a potential route for introducing certain groups at any site of the 2-aryl benzoxazole scaffold.

[Communications]
Yong Zhang, Min Ji
doi.org/10.1002/ejoc.201901468

New Strategy for the Synthesis of Heterocycles via Copper-Catalyzed Oxidative Decarboxylative Amination of Glyoxylic Acid

Articles from Wiley - 21 November, 2019 - 00:00

A copper-catalyzed oxidative decarboxylative amination of glyoxylic acid with substrates having two nitrogen-nucleophilic sites was first demonstrated, affording 1,3,5-triazines, quinazolinones and quinazolines in up to 93 % yields.

[Communications]
Bin Niu, Shaoqing Li, Chang Cui, Yizhe Yan, Lin Tang, Jianyong Wang
doi.org/10.1002/ejoc.201901538

Diastereoconvergent Dehydrative Nucleophilic Substitutions of Diastereomeric Diarylmethanols with 1,3-Dicarbonyls Catalyzed by SnBr<sub>4</sub>

Articles from Wiley - 21 November, 2019 - 00:00

SnBr4-catalyzed direct dehydrative substitution of diastereomeric mixtures of diarylmethanols with 1,3-dicarbonyl compounds was achieved in high yields and diastereoselectivities in a chiral inductive diastereoconvergent fashion.

[Communications]
Rikiya Kubo, Hiroshi Yamamoto, Kenya Nakata
doi.org/10.1002/ejoc.201901377

Carbonylative Negishi-Type Coupling of 2-Iodoglycals with Alkyl and Aryl Halides

Articles from Wiley - 21 November, 2019 - 00:00

A versatile C(sp2)-C(sp3) carbonylative Negishi-type reaction allowing the access to glyco-ketones bearing alkyl and aryl groups is described in this report. The tolerance for different functional groups as well as protecting groups denote the usefulness of the methodology.

[Full Papers]
Henrique A. Esteves, Mariana P. Darbem, Daniel C. Pimenta, Hélio A. Stefani
doi.org/10.1002/ejoc.201901081

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